A novel approach to determine the inverse kinematics of a human upper limb model with 9 degrees of freedom

Inverse kinematic calculation of detailed biomechanical models of the human upper limb has been known to be a daunting computational exercise. This paper presents a 9-degree of freedom (DoF) human upper limb biomechanical model with a novel algorithm to compute inverse kinematics. Inverse kinematics was realized using a successive frame rotation technique at joint level. The algorithm involves eliminating the system error and the redundancy by determining each joint angle one at a time. The proposed method starts from the base joint of the kinematic model and works forwards, determining each joint angle and the link orientation along the way. The proposed inverse kinematic algorithm was verified using accurate 3 dimensional (3D) motion data obtained for a human participant in an upper arm tennis serving scenario. Data were collected from a UK county level right-handed professional tennis player, using a six camera Qualisis motion capturing system at a rate of 240 Hz. The 9-DoF model enables detailed analysis of the motion of the upper human limb including the synchronous motion of sub-joints of the shoulder whilst the proposed inverse kinematic algorithm provides mathematically stable and robust results.